Abstract: Objective : To investigate the frequency of loss of heterozygosity (LOH) at chro-mosome 3p14.2, and 3p25 in non-small cell lung cancer (NSCLC) tissues. Methods : 44 NSCLCsamples were isolated using microdissection technique and DNAs were purified from tumor andnon-tumor tissues section respectively. DNA samples were amplified with microsatellite markers onthe following loci: 3p14.2(351228) and 3p25(351038) by using PCR. Results : It was found that3p14.2 LOH occurred in 19 of 29 (65.5%) NSCLC samples and 3p25 LOH happened in 6 of 15(40%) respectively, while there was no 3p LOH to be observed in normal tissues. The frequencyof LOH at 3p is not relative to TNM staging and pathological classification of NSCLC. Conclusion : Since 3p14.2 and 3p25 LOH occur commonly in human NSCLC, it was suggested that thetwo chromosomal regions might harbor one or more suppressor genes involving in the carcinogene-sis of NSCT.C.